Spherical bearings in general are not sealed, since they are usually mounted in some form of a bearing housing, whereby it is sufficient to seal the area where the shaft passes through the housing wall. However, sealed spherical bearings are commonly known. A problem with sealing of spherical bearings is that the sealing action of the seals are affected by the tilting of the bearing. The seal area on one side can be pressed harder against a contact surface while the seal area on the other side might have a loose contact depending on the degree of tilt. A seal being pressed too hard against a corresponding contact surface does not naturally degrade the sealing action in itself. However, this condition usually results in an unnecessarily high and undesirable friction. The contact between the seal and the corresponding contact surface becoming too loose does, of itself, naturally degrade the sealing action. Special designs of the seals for the spherical bearings therefore have been developed which withstand tilting of the bearing without increasing friction or degrading the sealing action.
The seals in spherical bearings are generally mounted on the outer ring, either in a groove on the side surface of the outer ring, or in a groove at the inner surface of the outer ring adjacent the spherical raceway path. If the groove is positioned on the side surface of the outer ring, the seal will mostly lie outside the bearing and a problem will arise when the bearing is mounted, since the side wall is occupied by the seal. During the mounting of the bearing, one has to consider that there has to be a space for the seal on the outside of the bearing. However, this is not a great problem.
When there is no space to permit mounting the seal outside the bearing then the seal must be mounted in a groove in the inner surface of the outer ring as discussed above. The bearing rings however, will be much broader than that required for the carrying capacity, since there has to be additional space inside the bearing, beside the roller elements, for the seals.